892 



FOODS AND FOOD ADULTERANTS. 



decanted each time and the fractious united. The decanted solution is now boiled 

 and passed through a tared filter. The insoluble residue is finally transferred to 

 this filter, thoroughly washed with boiling wat-r, dried, and weighed. The total 

 weight, less the tare of the filter, is the insoluble residue from which the per cent 

 insoluble leaf is calculated. The total extract is determined by difference, deducting 

 the per cent of insoluble leaf from 100. 



A weighing tube should be used in weighing filters and residues on filters. 



Half-hour extracts. This extract is of doubtful value for comparative purposes 

 unless certain conditions are adopted and strictly adhered to. Slight variations may 

 cause very perceptible errors in the results. I have followed essentially the condi- 

 tions indicated by Geisler, which are evidently based on Wanklyu's method. 



Place 1 gram of leaf tea in a 300 cc flask, add 100 cc cold distilled water and a small 

 fragment of paraffin, to prevent foaming. Immerse the flask a minute or two in 

 water heated to 90C. in order to raise the temperature of its contents quickly to 

 within a few degrees of the boiling point. Having dried the outside of the flask, 

 boil the mixture thirty minutes. The flask must be fitted Avith a reflux condenser. 

 After boiling, cool quickly in a stream of water and filter off the extract. Transfer 

 an aliquot part of the extract to a tarred dish aud dry. Calculate the per cent of 

 matter from the weight of the residue. 



GENERAL, REMARKS TO ANALYSTS. 



The analyst must be guided almost entirely by comparisons of his 

 work on the suspected teas with the records of analyses of pure sam- 

 ples. The microscopic are almost the sole methods of detecting many 

 of the adulterants of teas. Questions in regard to quality, where this 

 depends upon aroma only, must be answered by a professional tea- 

 taster. 



REPORT OF THE EXAMINATION OF SAMPLES OF TEAS BOUGHT IN 



THE OPEN MARKET. 



The samples examined in the course of the investigations were pur- 

 chased in stores of all grades. The analyses of these teas and general 

 statements concerning them are given in the following tables: 



Description of samples. 



